Roundup: Seventeen SAS Hard Disk Drives. Page 14

In our today’s roundup e are going to take a closer look at 17 SAS HDDs with storage capacities from 74 GB to 600 GB launched over the past several years. Find out who the winner is in the today’s SAS arena.

Web-Server, File-Server and Workstation Patterns

The drives are tested under loads typical of servers and workstations.

The names of the patterns are self-explanatory. The Workstation pattern is used with the full capacity of the drive as well as with a 32GB partition. The request queue is limited to 32 requests in the Workstation pattern.

The results are presented as performance ratings. For the File-Server and Web-Server patterns the performance rating is the average speed of the drive under every load. For the Workstation pattern we use the following formula:

This pattern consists of read requests only and we can see different leaders here. At short queue depths there are no rivals to the two newest generations of Seagate drives. The Maxtor is the only other drive that can get close to them. When it comes to maximum speed achievable, there are a lot of models that claim the leadership: Fujitsu’s MBA3 RC series (except for the 300GB model), Hitachi’s two newest series, and the Seagate 15K.7.

You should also note at what queue depth each HDD reaches its top speed. We’ve got two roughly equal groups here: one group accelerates up to a queue depth of 64 requests while the other goes on speeding up to a queue depth of 128 requests. The Seagate 15K.6 series shows a queer behavior: its performance indeed lowers after the queue grows longer than 64 requests.

The standings might have been predicted: first place goes to the newest Seagate 15K.7. The Seagate 15K.6 drives are second and third thanks to their excellent speed at short queue depths. The Maxtor is fourth.

The 10,000rpm model is no competitor to the grownups here. It can only beat the 300GB Fujitsu which has obvious problems with reading.

The overall picture does not change much when there are some write requests in the pattern. We’ve got the same winners at short queue depths and the same highest-speed models. The Seagate 15K.6 series slow down at queue depths longer than 64 requests, again. We want to note one thing here: the Maxtor and the Seagate 15K.4 stop accelerating at a queue depth of only 32 requests. It looks like this limitation is due to their having only 8 megabytes of cache.

We see the same HDDs at the top of the diagram, the only difference being the 146GB Seagate 15K.6 which has sunk to the middle of the list.